initial commit DRQN implementation

hive/agents/__init__.py

@@ -1,6 +1,7 @@
 from hive.agents import qnets
 from hive.agents.agent import Agent
 from hive.agents.dqn import DQNAgent
+from hive.agents.drqn import DRQNAgent
 from hive.agents.legal_moves_rainbow import LegalMovesRainbowAgent
 from hive.agents.rainbow import RainbowDQNAgent
 from hive.agents.random import RandomAgent
@@ -13,6 +14,7 @@
         "LegalMovesRainbowAgent": LegalMovesRainbowAgent,
         "RainbowDQNAgent": RainbowDQNAgent,
         "RandomAgent": RandomAgent,
+        "DRQNAgent": DRQNAgent,
     },
 )
 

hive/agents/dqn.py

@@ -112,7 +112,7 @@ def __init__(
         self._replay_buffer = replay_buffer
         if self._replay_buffer is None:
             self._replay_buffer = CircularReplayBuffer()
-        self._discount_rate = discount_rate ** n_step
+        self._discount_rate = discount_rate**n_step
         self._grad_clip = grad_clip
         self._reward_clip = reward_clip
         self._target_net_soft_update = target_net_soft_update

hive/agents/drqn.py

@@ -0,0 +1,288 @@
+import copy
+import os
+
+import numpy as np
+import torch
+
+from hive.agents.agent import Agent
+from hive.agents.qnets.base import FunctionApproximator
+from hive.agents.qnets.qnet_heads import DQNNetwork
+from hive.agents.qnets.utils import (
+    InitializationFn,
+    calculate_output_dim,
+    create_init_weights_fn,
+)
+from hive.replays import BaseReplayBuffer, CircularReplayBuffer
+from hive.utils.loggers import Logger, NullLogger
+from hive.utils.schedule import (
+    LinearSchedule,
+    PeriodicSchedule,
+    Schedule,
+    SwitchSchedule,
+)
+from hive.agents.dqn import DQNAgent
+from hive.utils.utils import LossFn, OptimizerFn, create_folder, seeder
+
+
+class DRQNAgent(DQNAgent):
+    """An agent implementing the DQN algorithm. Uses an epsilon greedy
+    exploration policy
+    """
+
+    def __init__(
+        self,
+        representation_net: FunctionApproximator,
+        obs_dim,
+        act_dim: int,
+        id=0,
+        optimizer_fn: OptimizerFn = None,
+        loss_fn: LossFn = None,
+        init_fn: InitializationFn = None,
+        replay_buffer: BaseReplayBuffer = None,
+        discount_rate: float = 0.99,
+        n_step: int = 1,
+        grad_clip: float = None,
+        reward_clip: float = None,
+        update_period_schedule: Schedule = None,
+        target_net_soft_update: bool = False,
+        target_net_update_fraction: float = 0.05,
+        target_net_update_schedule: Schedule = None,
+        epsilon_schedule: Schedule = None,
+        test_epsilon: float = 0.001,
+        min_replay_history: int = 5000,
+        batch_size: int = 32,
+        device="cpu",
+        logger: Logger = None,
+        log_frequency: int = 100,
+    ):
+        """
+        Args:
+            representation_net (FunctionApproximator): A network that outputs the
+                representations that will be used to compute Q-values (e.g.
+                everything except the final layer of the DQN).
+            obs_dim: The shape of the observations.
+            act_dim (int): The number of actions available to the agent.
+            id: Agent identifier.
+            optimizer_fn (OptimizerFn): A function that takes in a list of parameters
+                to optimize and returns the optimizer. If None, defaults to
+                :py:class:`~torch.optim.Adam`.
+            loss_fn (LossFn): Loss function used by the agent. If None, defaults to
+                :py:class:`~torch.nn.SmoothL1Loss`.
+            init_fn (InitializationFn): Initializes the weights of qnet using
+                create_init_weights_fn.
+            replay_buffer (BaseReplayBuffer): The replay buffer that the agent will
+                push observations to and sample from during learning. If None,
+                defaults to
+                :py:class:`~hive.replays.circular_replay.CircularReplayBuffer`.
+            discount_rate (float): A number between 0 and 1 specifying how much
+                future rewards are discounted by the agent.
+            n_step (int): The horizon used in n-step returns to compute TD(n) targets.
+            grad_clip (float): Gradients will be clipped to between
+                [-grad_clip, grad_clip].
+            reward_clip (float): Rewards will be clipped to between
+                [-reward_clip, reward_clip].
+            update_period_schedule (Schedule): Schedule determining how frequently
+                the agent's Q-network is updated.
+            target_net_soft_update (bool): Whether the target net parameters are
+                replaced by the qnet parameters completely or using a weighted
+                average of the target net parameters and the qnet parameters.
+            target_net_update_fraction (float): The weight given to the target
+                net parameters in a soft update.
+            target_net_update_schedule (Schedule): Schedule determining how frequently
+                the target net is updated.
+            epsilon_schedule (Schedule): Schedule determining the value of epsilon
+                through the course of training.
+            test_epsilon (float): epsilon (probability of choosing a random action)
+                to be used during testing phase.
+            min_replay_history (int): How many observations to fill the replay buffer
+                with before starting to learn.
+            batch_size (int): The size of the batch sampled from the replay buffer
+                during learning.
+            device: Device on which all computations should be run.
+            logger (ScheduledLogger): Logger used to log agent's metrics.
+            log_frequency (int): How often to log the agent's metrics.
+        """
+        super().__init__(
+            representation_net=representation_net,
+            obs_dim=obs_dim,
+            act_dim=act_dim,
+            id=0,
+            optimizer_fn=optimizer_fn,
+            loss_fn=loss_fn,
+            init_fn=init_fn,
+            replay_buffer=replay_buffer,
+            discount_rate=discount_rate,
+            n_step=n_step,
+            grad_clip=grad_clip,
+            reward_clip=reward_clip,
+            update_period_schedule=update_period_schedule,
+            target_net_soft_update=target_net_soft_update,
+            target_net_update_fraction=target_net_update_fraction,
+            target_net_update_schedule=target_net_update_schedule,
+            epsilon_schedule=epsilon_schedule,
+            test_epsilon=test_epsilon,
+            min_replay_history=min_replay_history,
+            batch_size=batch_size,
+            device=device,
+            logger=logger,
+            log_frequency=log_frequency,
+        )
+
+    def create_q_networks(self, representation_net):
+        """Creates the Q-network and target Q-network.
+
+        Args:
+            representation_net: A network that outputs the representations that will
+                be used to compute Q-values (e.g. everything except the final layer
+                of the DQN).
+        """
+        network = representation_net(self._obs_dim)
+        network_output_dim = np.prod(calculate_output_dim(network, self._obs_dim))
+        self._qnet = DQNNetwork(
+            network, network_output_dim, self._act_dim, use_rnn=True
+        ).to(self._device)
+        self._qnet.apply(self._init_fn)
+        self._target_qnet = copy.deepcopy(self._qnet).requires_grad_(False)
+
+    def preprocess_update_info(self, update_info):
+        """Preprocesses the :obj:`update_info` before it goes into the replay buffer.
+        Clips the reward in update_info.
+
+        Args:
+            update_info: Contains the information from the current timestep that the
+                agent should use to update itself.
+        """
+        if self._reward_clip is not None:
+            update_info["reward"] = np.clip(
+                update_info["reward"], -self._reward_clip, self._reward_clip
+            )
+        preprocessed_update_info = {
+            "observation": update_info["observation"],
+            "action": update_info["action"],
+            "reward": update_info["reward"],
+            "done": update_info["done"],
+        }
+        if "agent_id" in update_info:
+            preprocessed_update_info["agent_id"] = int(update_info["agent_id"])
+
+        return preprocessed_update_info
+
+    def preprocess_update_batch(self, batch):
+        """Preprocess the batch sampled from the replay buffer.
+
+        Args:
+            batch: Batch sampled from the replay buffer for the current update.
+
+        Returns:
+            (tuple):
+                - (tuple) Inputs used to calculate current state values.
+                - (tuple) Inputs used to calculate next state values
+                - Preprocessed batch.
+        """
+        for key in batch:
+            batch[key] = torch.tensor(batch[key], device=self._device)
+        return (batch["observation"],), (batch["next_observation"],), batch
+
+    @torch.no_grad()
+    def act(self, observation):
+        """Returns the action for the agent. If in training mode, follows an epsilon
+        greedy policy. Otherwise, returns the action with the highest Q-value.
+
+        Args:
+            observation: The current observation.
+        """
+
+        # Determine and log the value of epsilon
+        if self._training:
+            if not self._learn_schedule.get_value():
+                epsilon = 1.0
+            else:
+                epsilon = self._epsilon_schedule.update()
+            if self._logger.update_step(self._timescale):
+                self._logger.log_scalar("epsilon", epsilon, self._timescale)
+        else:
+            epsilon = self._test_epsilon
+
+        # Sample action. With epsilon probability choose random action,
+        # otherwise select the action with the highest q-value.
+        observation = torch.tensor(
+            np.expand_dims(observation, axis=0), device=self._device
+        ).float()
+        qvals = self._qnet(observation)
+        if self._rng.random() < epsilon:
+            action = self._rng.integers(self._act_dim)
+        else:
+            # Note: not explicitly handling the ties
+            action = torch.argmax(qvals).item()
+
+        if (
+            self._training
+            and self._logger.should_log(self._timescale)
+            and self._state["episode_start"]
+        ):
+            self._logger.log_scalar("train_qval", torch.max(qvals), self._timescale)
+            self._state["episode_start"] = False
+        return action
+
+    def update(self, update_info):
+        """
+        Updates the DQN agent.
+
+        Args:
+            update_info: dictionary containing all the necessary information to
+                update the agent. Should contain a full transition, with keys for
+                "observation", "action", "reward", and "done".
+        """
+        if update_info["done"]:
+            self._state["episode_start"] = True
+
+        if not self._training:
+            return
+
+        # Add the most recent transition to the replay buffer.
+        self._replay_buffer.add(**self.preprocess_update_info(update_info))
+
+        # Update the q network based on a sample batch from the replay buffer.
+        # If the replay buffer doesn't have enough samples, catch the exception
+        # and move on.
+        if (
+            self._learn_schedule.update()
+            and self._replay_buffer.size() > 0
+            and self._update_period_schedule.update()
+        ):
+            batch = self._replay_buffer.sample(batch_size=self._batch_size)
+            (
+                current_state_inputs,
+                next_state_inputs,
+                batch,
+            ) = self.preprocess_update_batch(batch)
+
+            # Compute predicted Q values
+            self._optimizer.zero_grad()
+            pred_qvals = self._qnet(*current_state_inputs)
+            actions = batch["action"].long()
+            pred_qvals = pred_qvals[torch.arange(pred_qvals.size(0)), actions]
+
+            # Compute 1-step Q targets
+            next_qvals = self._target_qnet(*next_state_inputs)
+            next_qvals, _ = torch.max(next_qvals, dim=1)
+
+            q_targets = batch["reward"] + self._discount_rate * next_qvals * (
+                1 - batch["done"]
+            )
+
+            loss = self._loss_fn(pred_qvals, q_targets).mean()
+
+            if self._logger.should_log(self._timescale):
+                self._logger.log_scalar("train_loss", loss, self._timescale)
+
+            loss.backward()
+            if self._grad_clip is not None:
+                torch.nn.utils.clip_grad_value_(
+                    self._qnet.parameters(), self._grad_clip
+                )
+            self._optimizer.step()
+
+        # Update target network
+        if self._target_net_update_schedule.update():
+            self._update_target()

hive/agents/qnets/__init__.py

@@ -3,12 +3,14 @@
 from hive.agents.qnets.base import FunctionApproximator
 from hive.agents.qnets.conv import ConvNetwork
 from hive.agents.qnets.mlp import MLPNetwork
+from hive.agents.qnets.rnn import ConvRNNNetwork
 
 registry.register_all(
     FunctionApproximator,
     {
         "MLPNetwork": FunctionApproximator(MLPNetwork),
         "ConvNetwork": FunctionApproximator(ConvNetwork),
+        "ConvRNNNetwork": FunctionApproximator(ConvRNNNetwork),
         "NatureAtariDQNModel": FunctionApproximator(NatureAtariDQNModel),
     },
 )